Tesla announced today that its third-quarter revenues hit $603 million, up 9 percent over Q2 and with a 25-percent gross profit margin expected by the end of the year.

But its revenue and unit sales fell short of expectations, and investors sent its shares down 12 percent to $154 in after-hours trading.

The Hawthorne, Calif.-based automaker is producing 550 cars per week and finished the quarter with a record 5,500 deliveries, including 1,000 deliveries to Europe.

Founder Elon Musk said annual sales of Tesla cars in North America alone could easily skyrocket above the 20,000-unit mark but that production—particularly of battery cells—limits growth.

“It doesn’t make sense for us to amplify that demand if we aren’t able to deliver on that demand,” he told reporters late Tuesday. “It just makes people unhappy.”

Musk said Tesla will deliver roughly 6,000 Model S vehicles in Q4, a total increase to 21,500 vehicles sold worldwide for 2013.

“We expect to alleviate a lot of those production constraints next year,” Musk said.

Indeed, the company recently expanded its 2011 supplier agreement with to allow for increased production capacity of automotive-grade lithium-ion battery cells at a minimum of 1.8 billion cells over four years, more than three times the previous agreement. The number should be viewed as more of a floor than a ceiling, according to Q3 reports.

In the meantime, Tesla had to stop North American demand in order to feed Europe even as it began to take reservations in China during the quarter. Musk said he anticipates Model S deliveries there to begin in Q1 2014, which will significantly increase overall demand as well.

The current wait time for a Model S in China is six months.

“I would certainly recommend anyone who does want to get the car to place the order pretty soon,” Musk said. “In other words the longer you wait the longer you will have to wait.”

Another key to growth at Tesla has been expansion of its supercharger network, which involves 31 stations open in North America and six new stations in Norway. The network allows Tesla owners to travel cross-country without inducing range-anxiety.

Tesla says 90 percent of its customers opt for supercharging capability and nearly a third of all Model S cars have been supercharged at least once. That is the equivalent of driving 4 million electric miles and saving nearly 200,000 gallons of fuel.

With that in mind, Tesla plans to cover Germany with complete supercharger range by mid-2014 and by the end of 2014 enable Holland, Switzerland, Belgium, Austria, Denmark and Luxembourg and 90 percent of the population in England, Wales and Sweden to live within 200 miles of a supercharger station.

For his part Musk said he will spend the next few quarters working to develop Tesla's third-generation vehicle and helping foster increased production.

Until then—in some markets at least—Tesla will have to hold back, he says: “We’re not even really trying.”